# Copyright 2010 Hakan Kjellerstrand hakank@bonetmail.com
#
# Licensed under the Apache License, Version 2.0 (the 'License');
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an 'AS IS' BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""
Safe cracking puzzle in Google CP Solver.
From the Oz Primer:
http://www.comp.nus.edu.sg/~henz/projects/puzzles/digits/index.html
'''
The code of Professor Smart's safe is a sequence of 9 distinct
nonzero digits C1 .. C9 such that the following equations and
inequations are satisfied:
C4 - C6 = C7
C1 * C2 * C3 = C8 + C9
C2 + C3 + C6 < C8
C9 < C8
and
C1 <> 1, C2 <> 2, ..., C9 <> 9
can you find the correct combination?
'''
Compare with the following models:
* MiniZinc: http://www.hakank.org/minizinc/safe_cracking.mzn
* ECLiPSe : http://www.hakank.org/eclipse/safe_cracking.ecl
* SICStus : http://www.hakank.org/sicstus/safe_cracking.pl
* Gecode: http://hakank.org/gecode/safe_cracking.cpp
This model was created by Hakan Kjellerstrand (hakank@bonetmail.com)
Also see my other Google CP Solver models:
http://www.hakank.org/google_or_tools/
"""
from ortools.constraint_solver import pywrapcp
def main():
# Create the solver.
solver = pywrapcp.Solver('Safe cracking puzzle')
#
# data
#
n = 9
digits = range(1, n + 1)
#
# variables
#
LD = [solver.IntVar(digits, 'LD[%i]' % i) for i in range(n)]
C1, C2, C3, C4, C5, C6, C7, C8, C9 = LD
#
# constraints
#
solver.Add(solver.AllDifferent(LD))
solver.Add(C4 - C6 == C7)
solver.Add(C1 * C2 * C3 == C8 + C9)
solver.Add(C2 + C3 + C6 < C8)
solver.Add(C9 < C8)
for i in range(n):
solver.Add(LD[i] != i + 1)
#
# search and result
#
db = solver.Phase(LD,
solver.INT_VAR_DEFAULT,
solver.INT_VALUE_DEFAULT)
solver.NewSearch(db)
num_solutions = 0
while solver.NextSolution():
num_solutions += 1
print 'LD:', [LD[i].Value() for i in range(n)]
solver.EndSearch()
print
print 'num_solutions:', num_solutions
print 'failures:', solver.Failures()
print 'branches:', solver.Branches()
print 'WallTime:', solver.WallTime(), 'ms'
if __name__ == '__main__':
main()